The present invention is generally related to communications systems and more particularly to an improved method and apparatus for substantially enhancing the stability of data communications systems subjected to peak loads demanding 100% of system capacity.
Prior art data communications systems must be operated at 30 to 50% of their capacity in order to accommodate peak expected loads. Furthermore, if the actual peak load demands 100% of system capacity, such prior art data communications systems will crash. Such catastrophic failures are not acceptable in multi-user data communications systems.
Prior art data communications systems typically must acknowledge an inbound message within a few seconds, or the inbound message will be re-asserted. As the system load increases it takes longer and longer to return the acknowledgement message. During peak loads, the acknowledge takes so long that the inbound messages are re-asserted before any acknowledgement messages are returned by the communications controller. Catastrophic regeneration is produced since more load is put on the communications controller, which in turn further increases the acknowledge response time. Thus, such prior art data communications systems become unstable and crash when subjected to inbound message loads demanding 100% of system capacity.
In some prior art data communications systems, a slow down message can be used to reduce the frequency of inbound messages. However, the necessity of sending such slow down messages to every message source both adds to the load and may cause the communications controller to become unstable and crash. Moreover, the use of slow down messages does not accommodate recurring short duration peak loads demanding 100% of system capacity. Other techniques limiting the number of input message buffers or buffer length are likewise inadequate since peak loads may demand 100% of system capacity while buffers are free, and ignoring further messages when buffers are full may result in the loss of inbound messages that will not be re-asserted.